Set default focus behavior for views button subclasses

Other than BaseScrollBarButton, other subclasses of Button class in
views/ should follow Button's default focus behavior.
BaseScrollBarButton should not be focusable, nor accessible for
accessibility.
Set these default values explicitly so changing Button class's default
won't affect them.

Bug: 1001103
Change-Id: If32d8dadf69a5ba5f8d23738678e31d285d3e5ab
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2429435
Commit-Queue: Wei Li <weili@chromium.org>
Reviewed-by: Michael Wasserman <msw@chromium.org>
Cr-Commit-Position: refs/heads/master@{#813451}

ui/views/controls/button/image_button.cc

@@ -34,6 +34,8 @@ ImageButton::ImageButton(PressedCallback callback)
   // implementation is flipped horizontally so that the button's images are
   // mirrored when the UI directionality is right-to-left.
   EnableCanvasFlippingForRTLUI(true);
+  // Not focusable by default, only for accessibility.
+  SetFocusBehavior(FocusBehavior::ACCESSIBLE_ONLY);
 }
 
 ImageButton::ImageButton(ButtonListener* listener)

ui/views/controls/button/image_button_unittest.cc

@@ -39,6 +39,12 @@ namespace views {
 
 using ImageButtonTest = ViewsTestBase;
 
+TEST_F(ImageButtonTest, FocusBehavior) {
+  ImageButton button;
+
+  EXPECT_EQ(View::FocusBehavior::ACCESSIBLE_ONLY, button.GetFocusBehavior());
+}
+
 TEST_F(ImageButtonTest, Basics) {
   ImageButton button;
 

ui/views/controls/button/label_button.cc

@@ -40,6 +40,8 @@ LabelButton::LabelButton(PressedCallback callback,
           style::GetFont(button_context, style::STYLE_PRIMARY)),
       cached_default_button_font_list_(
           style::GetFont(button_context, style::STYLE_DIALOG_BUTTON_DEFAULT)) {
+  // Not focusable by default, only for accessibility.
+  SetFocusBehavior(FocusBehavior::ACCESSIBLE_ONLY);
   ink_drop_container_ = AddChildView(std::make_unique<InkDropContainerView>());
   ink_drop_container_->SetVisible(false);
 

ui/views/controls/button/label_button_unittest.cc

@@ -141,6 +141,12 @@ class LabelButtonTest : public test::WidgetTest {
   DISALLOW_COPY_AND_ASSIGN(LabelButtonTest);
 };
 
+TEST_F(LabelButtonTest, FocusBehavior) {
+  LabelButton button;
+
+  EXPECT_EQ(View::FocusBehavior::ACCESSIBLE_ONLY, button.GetFocusBehavior());
+}
+
 TEST_F(LabelButtonTest, Init) {
   const base::string16 text(ASCIIToUTF16("abc"));
   TestLabelButton button(text);

ui/views/controls/scrollbar/base_scroll_bar_button.cc

@@ -16,7 +16,10 @@ BaseScrollBarButton::BaseScrollBarButton(ButtonListener* listener,
     : Button(listener),
       repeater_(base::BindRepeating(&BaseScrollBarButton::RepeaterNotifyClick,
                                     base::Unretained(this)),
-                tick_clock) {}
+                tick_clock) {
+  // Not focusable by default.
+  SetFocusBehavior(FocusBehavior::NEVER);
+}
 
 BaseScrollBarButton::~BaseScrollBarButton() = default;
 

ui/views/controls/scrollbar/base_scroll_bar_button_unittest.cc

@@ -71,6 +71,10 @@ TEST_F(BaseScrollBarButtonTest, Metadata) {
   test::TestViewMetadata(button());
 }
 
+TEST_F(BaseScrollBarButtonTest, FocusBehavior) {
+  EXPECT_EQ(View::FocusBehavior::NEVER, button()->GetFocusBehavior());
+}
+
 TEST_F(BaseScrollBarButtonTest, CallbackFiresOnMouseDown) {
   EXPECT_CALL(listener(), ButtonPressed(_, _));
 

ui/views/controls/scrollbar/scroll_bar_views.cc

@@ -75,7 +75,7 @@ class ScrollBarThumb : public BaseScrollBarThumb {
 ScrollBarButton::ScrollBarButton(ButtonListener* listener, Type type)
     : BaseScrollBarButton(listener), type_(type) {
   EnableCanvasFlippingForRTLUI(true);
-  SetFocusBehavior(FocusBehavior::NEVER);
+  DCHECK_EQ(FocusBehavior::NEVER, GetFocusBehavior());
 }
 
 ScrollBarButton::~ScrollBarButton() = default;

ui/views/window/frame_caption_button.cc

@@ -77,6 +77,8 @@ FrameCaptionButton::FrameCaptionButton(views::ButtonListener* listener,
       ink_drop_corner_radius_(kCaptionButtonInkDropDefaultCornerRadius),
       swap_images_animation_(new gfx::SlideAnimation(this)) {
   views::SetHitTestComponent(this, hit_test_type);
+  // Not focusable by default, only for accessibility.
+  SetFocusBehavior(FocusBehavior::ACCESSIBLE_ONLY);
 
   SetAnimateOnStateChange(true);
   swap_images_animation_->Reset(1);

ui/views/window/frame_caption_button_unittest.cc

@@ -6,7 +6,10 @@
 
 #include "testing/gtest/include/gtest/gtest.h"
 #include "third_party/skia/include/core/SkColor.h"
+#include "ui/base/hit_test.h"
 #include "ui/gfx/color_utils.h"
+#include "ui/views/view.h"
+#include "ui/views/window/caption_button_types.h"
 
 namespace {
 
@@ -20,10 +23,18 @@ constexpr SkColor kBackgroundColors[] = {
 
 }  // namespace
 
+namespace views {
+
 TEST(FrameCaptionButtonTest, ThemedColorContrast) {
   for (SkColor background_color : kBackgroundColors) {
-    SkColor button_color =
-        views::FrameCaptionButton::GetButtonColor(background_color);
+    SkColor button_color = FrameCaptionButton::GetButtonColor(background_color);
     EXPECT_GE(color_utils::GetContrastRatio(button_color, background_color), 3);
   }
 }
+
+TEST(FrameCaptionButtonTest, DefaultAccessibilityFocus) {
+  FrameCaptionButton button(nullptr, CAPTION_BUTTON_ICON_MINIMIZE, HTMINBUTTON);
+  EXPECT_EQ(View::FocusBehavior::ACCESSIBLE_ONLY, button.GetFocusBehavior());
+}
+
+}  // namespace views